SN54ACT8997, SN74ACT8997

SCAN-PATH LINKERS WITH 4-BIT IDENTIFICATION BUSES

SCAN-CONTROLLED IEEE STD 1149.1 (JTAG) TAP CONCATENATORS

SCAS157D – APRIL 1990 – REVISED DECEMBER 1996

16

POST OFFICE BOX 655303

data flow description

The direction of serial-data flow in the ’ACT8997 is dependent on the current instruction and value of the SR.

Figure 8 shows the data flow when one or more SSPs have been selected. When more than one SSP has been

selected, the order of scan is determined by which SSPs have been selected as shown in Table 9. The ’ACT8997

add one bit of delay from TDI or DTDI to DTDO.

TDI

DTDOn

TDI

TDO

DTDIn

TDO

(1-bit delay)

SSPn

TDI

TDO

IR or

Selected DR

Selected Scan Path

NO SECONDARY SCAN PATH SELECTED

ONE SECONDARY SCAN PATH SELECTED

TDI

DTDOx

TDI

TDO

DTDIm

TDO

(1-bit delay)

SSPx

IR or

Selected DR

Selected Scan Path

MULTIPLE SECONDARY SCAN PATHS SELECTED

DTDIx

DTDOn

(1-bit delay)

TDI

TDO

SSPn

Selected Scan Path

DTDIn

DTDOm

(1-bit delay)

TDI

TDO

SSPm

Selected Scan Path

’ACT8997

’ACT8997

’ACT8997

’ACT8997

’ACT8997

’ACT8997

’ACT8997

IR or

Selected DR

Figure 8. Data Flow in the ’ACT8997